Executive Assistant, (Commercial/Human Resources) & Office Manager

Definium Therapeutics is a late-stage clinical biopharmaceutical company and our mission is to forge a new era of psychiatry by applying scientific rigor to psychedelics, with the goal of developing accessible treatments that unlock healing at scale. Our lead product candidate, lysergide tartrate (our proprietary orally disintegrating tablet form of lysergide (LSD) D-tartrate), represents a highly differentiated, potential best-in-class opportunity for patients suffering from generalized anxiety, major depressive disorder, and posttraumatic stress disorder. Our early stage pipeline includes DT402, the R-enantiomer of MDMA and is under development to target the core symptoms of autism spectrum disorder (ASD), specifically addressing social communication challenges. Guided by the recognition that patients deserve more than better, Definium is relentlessly advancing a new generation of therapeutics intended to address the underlying causes of psychiatric and neurological disorders. By turning evidence into impact, Definium aims to change the trajectory of today’s mental health care crisis and enable a healthier future. Headquartered in New York, Definium Therapeutics trades on Nasdaq under the symbol DFTX. Together we are moving psychiatry forward—beyond better, into a boundless future. Join us! The Executive Assistant, Commercial/Human Resources & Office Manager will provide executive, administrative, and operational support to the Commercial & Human Resources organizations providing the opportunity to support a broad range of leaders, activities, and strategic initiatives across the company while serving as a key coordinator for Definium's Radnor, PA office. This highly visible role supports the Chief Commercial Officer (CCO) and Head of Human Resources (Head of HR), as well as the functional leadership teams, coordinates commercial & HR activities, manages office operations, and partners closely with stakeholders across the organization to ensure seamless execution of meetings, travel, conferences, events, and day-to-day operations. This position has a dual reporting line into the Chief Commercial Officer and Head of Human Resources and works closely with leaders across the Commercial & HR functions, the Executive Leadership Team, and administrative partners throughout the company. Key responsibilities include but not limited to the following: Provide executive, administrative, and operational support to the CCO & Head of HR and their leadership teams Be on site in the Radnor office at a minimum of 3 days per week but sometimes more depending on the need for that week Coordinate domestic and international travel arrangements and related logistics Prepare itineraries, agendas, briefing materials, and meeting logistics Coordinate departmental meetings, offsites, team activities, and leadership events Screen and prioritize meeting requests while helping resolve scheduling conflicts Track action items and follow-ups from key meetings and leadership discussions Process expense reports, invoices, and other departmental administrative needs Support broader Commercial & HR team operations and special projects as needed Partner closely with executive assistants across the organization to coordinate schedules, travel, meetings, and executive priorities Serve as the primary coordinator for Definium's Radnor office Manage office operations, office supplies, workplace resources, facilities coordination, vendor relationships, and workplace services Coordinate onsite logistics for leadership meetings, team offsites, employee events, and executive visits Assist with logistics for meetings held in Radnor, including meeting space coordination, visitor support, catering, transportation, and related onsite activities. Assist with special projects and corporate initiatives as needed Qualifications: Bachelor’s degree or equivalent experience Minimum 7 years of experience supporting senior executives in a public company, biotechnology, life science…